Infant Born With Autosomal Recessive Glycogen Storage Disease Type IV due to Complete Maternal Isodisomy of Chromosome 3.

Uniparental disomy (UPD), the inheritance of two copies of a chromosome from one parent, can lead to recessive genetic disorders or imprinting effects. We report a case of autosomal recessive glycogen storage disease type 4 (GSD IV) due to maternal UPD of chromosome 3, representing the first reported instance of UPD leading to this rare disorder. To avoid an unjustified claim of misattributed paternity, the possibility of UPD should always be kept in mind in cases with the unique finding of the homozygous pathogenic variant only present in one parent. This case highlights the critical role of genetic counseling in uncovering rare genetic conditions and emphasizes the need for continued awareness of UPD in clinical genetics.